1. Field of the Invention
The invention relates to methods of and apparatus for bonding an article to a substrate. More particularly, the invention relates to methods of and apparatus for sequentially bonding small articles, such as semiconductor chips or other electronic device, to a substrate. Because of the small size of such devices, the invention relates to precision handling, and bonding of the devices and substrates.
2. Description of the Prior Art
In bonding an article such as an electronic device to a substrate, a generally known approach is to align the electronic device to a bonding axis and to temporarily hold it with a bonding tip along the bonding axis. Thereafter, a substrate is transferred to the bonding axis and a bond site on the substrate is aligned with respect to the bonding axis and to the previously aligned device to bring the device into contact with the substrate and to bond it thereto. Such basic methods and the respective apparatus are, for instance, disclosed in U.S. Pat. No. 3,477,630 to F. J. Schneider. The referred-to art provides for a magazine-type feed for the substrates and a movable holder for the semiconductor devices which permit the devices as well as the substrates to be brought into alignment with the bonding axis without difficulty.
However, such a precision alignment of the substrate as well as the device is always time consuming. It is consequently desirable to reduce and minimize the time intervals required to load and align the substrate to the semiconductor device to optimize the output of a particular bonding machihe. In U.S. Pat. No. 3,793,710 to Monahan et al. a solution other than feeding substrates from a magazine was provided that nevertheless optimized the time required to align the substrate with the chip.
In bonding small articles such as semiconductor devices to substrates, the bonding operation itself requires a relatively fixed time interval. In raising the hourly output of a bonder, it is therefore desirable to minimize time requirements which pertain to steps other than bonding of the device to the substrate. These are steps such as feeding a substrate and a device and aligning the substrate to the device, as well as unloading the bonded product from the bonder.